A Look at the Recent CDC Report Indicating a Rise in the Prevalence of Autism

In the wake of the recent report from the Centers for Disease Control and Prevention (CDC) and the National Survey of Children’s Health (NSCH), which indicates the autism prevalence rate has risen to 1 in 50 children in the United States, we at the National Autism Network thought it pertinent to the discuss the dramatic rise in autism rates. This news comes on the cusp of a previous report published by the CDC in early 2012 that indicates that 1 in 88 children in the United States have an autism diagnosis by age 8, based on data collected in 2008. While the data collection methods utilized in this most recent study were not the most rigorous (a parent survey), the impact of these statistics is significant. The phone survey data was collected from 2007 and 2011-2012 and indicates that 3.23% of boys and .7% of girls between the ages of 6 and 17 have an autism spectrum disorder diagnosis.1 These estimates indicate that at least 1 million children in the United States have an autism diagnosis 2, but what is causing this increased prevalence?

Autism experts tend to disagree on this matter. Some believe that the sky rocketing autism rates observed in the last decade and beyond are a result of an increased awareness and better diagnostic methods. Other individuals believe that the rise of prevalence is due to exposure of hazardous environmental factors (pesticides, pollution, vaccines, etc.). Sadly, this debate has been ongoing for over a decade with no clear answer. The most recent report released by the CDC dismisses survey-based measurement changes over time, stating that:

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The estimated prevalence of parent-reported ASD for children 6-17 in 2011-2012 whose ASD was diagnosed in or before 2007 was 1.37%...This estimate is statistically indistinguishable (p>.10) from the estimate for that same birth cohort from the 2007 NSCH, suggesting that survey-based measurement error was unlikely to have been a major contributor to the observed prevalence increases.3

The “Summary and Discussion” section of the CDC report delves into much greater detail about the likely causes of increased ASD prevalence observed in this report. The document states that:

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Evidence from epidemiologic, genetic, and neuroscience research points to the prenatal period as the key exposure window for ASD risk factors. If the causes of ASD are related to factors that exist prior to or occur just after birth, it is unlikely that changes in ASD prevalence within the cohorts of children aged 6–13 in 2011–2012 reflect ‘true’ increases in susceptibility to the condition at these ages. Rather, changes in prevalence of parent-reported ASD within these birth cohorts (children born in 1998–2005) likely reflect either changes in the recognition of ASD by health professionals or survey-based measurement changes over time.3

Roy Richard Grinker, a professor of anthropology at George Washington University and co-author of a 2011 study that found the autism rates in South Korea to be 1 in 38 children, echoes the sentiments of the of the CDC report in regards to the increase in prevalence. Referring to the South Korea study in an article published in USA Today, Grinker states “I don’t see any evidence that there’s a true increase in the prevalence of autism…I don’t look at that and ‘that’s so much higher than the U.S.’ I look at that as ‘the U.S. will catch up.’”1

However, there are some who believe that this rise of prevalence cannot entirely be accounted for simply through better awareness and diagnostic services. Uday Mehta, a neurodevelopmental pediatrician and director of the nondevelopment and behavioral pediatrics program at Children’s Specialized Hospital in Mountainside, New Jersey, states “I think it’s a combination. There are more incidents, and that, along with better diagnosis, account for the fact that the prevalency rates are higher. It suggests an increased pathology in terms of causative factors which we do not yet know.”4 During the 2012 Congressional Hearing on Autism, Dr. Mark Blaxill, the Government Affairs Committee of SafeMinds, stated in his testimony that “some people claim [the rise of ASD prevalence] isn’t real. That we’re just doing better diagnosis, that’s just wrong…even in the CDC studies they are using the same methodology. So, when you see those numbers rising it’s not because the methods are changing, it is because there are more cases.”5 Perhaps Michael Rosanoff, associate director of public health research and scientific review at Autism Speaks, said it best when he stated “[The National Health Statistics Reports] is an important study. It definitely adds to the picture, but it also adds to the mystery of what’s going on.” 6

What are your opinions concerning the rise in prevalence of autism spectrum disorders seen in the United States and across the globe? Do you believe it is a result of better data collection methodology, diagnostic measures, and awareness? Or, do you believe the increased prevalence stems from environmental exposure, or both? Please leave your comments below.

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